Buff Rock or Buff Orpington?

This is my first year ever having chickens, I purchased 4 Buff Orps from a local supplier - all hens. I noticed that only one has yellowish orange legs & feet. All others are a pale skin tone.
They are around 15 weeks old now. I was looking in a catalog and saw Buff Rocks have the same look as B.O.'s. Except they have that color legs/ feet. Anyone have any thoughts on this? Thanks.